1. Field
The present invention relates generally to wireless communications, and more specifically selecting a service provider system in a geographic region.
2. Background
Wireless communication devices, such as cellular telephones, are commonly used as a replacement for conventional telephone systems. A large number of service providers compete for market share in multiple geographic regions. A user typically subscribes to a selected service provider and uses a wireless telephone device that is compatible with the service provider.
A user typically has a contractual obligation to the service provider wherein all billing for the wireless telephone is provided by the service provider. Users typically select service providers based on the financial arrangements of the contract and upon the areas of service coverage provided by the service provider. When the user operates the wireless telephone in a “home” region, service to the wireless telephone is typically provided by the user-selected service provider. When the user is outside the home region, the wireless telephone is said to be operating in a “Roam” mode. When operating in the Roam mode, the wireless telephone may be connected to the user-selected service provider, or some other service provider if the user-selected service provider cannot provide service to the wireless telephone. In either case, billing still occurs through the user-selected service provider. In the former situation, billing may be provided directly from the service provider. In the latter case, the billing from the actual service provider is forwarded to the user-selected service provider.
The wireless telephone is typically preprogrammed with the data related to various service provider systems taking into account the particular capabilities of the wireless telephone. For example, it is well known that wireless telephones can operate in either an analog mode or a digital mode, and in a cellular band or a personal communication system (PCS) band. Some wireless telephones are capable of operating in both the analog mode and the digital mode (although only one mode at a time), and some wireless telephones are capable of operating in both the cellular band and the PCS band. For a wireless telephone to communicate effectively, it must be within the operational boundaries of a wireless communication system service provider that supports the same mode and band with which the wireless telephone was designed to operate.
When first powered up, wireless telephones scan for a service provider whose system is compatible with the wireless telephone. A data table or other suitable structure, sometimes referred to as a “Roaming” list or a “Preferred Roaming List” (PRL), provides data related to all possible service providers for the particular wireless telephone. The wireless telephone uses the Roaming list in an attempt to acquire service in a particular geographic region.
For purposes of illustration, suppose a user of a wireless telephone travels from the geographic region of their particular “Home” service provider (e.g., the wireless service provider with whom the user contracted to provide wireless service) to another geographic region and therefore is operating in the Roam mode. Under these circumstances, the wireless telephone must detect and acquire a wireless service provider system. In any given geographic region, wireless service provider systems may comprise analog system service providers, commonly referred to as an advanced mobile phone service (AMPS) system, or a digital system, such as, by way of example, a code division multiple access (CDMA) system. Because the wireless telephone has no advanced knowledge of the user's present geographic location, the wireless telephone selects the service provider system based on one or more selection criteria.
When powered on, the wireless telephone scans for any suitable wireless service provider based on criteria, such as signal strength of the wireless service provider's system, the wireless telephone's mode of operation, the wireless telephone's band of operation, and on the particular channel availability. The wireless telephone selects the first service provider system that it encounters that meets the criteria for the particular wireless telephone.
Wireless telephones are now being equipped to handle a Global System for Mobile Communications (GSM) digital mode as well as CDMA digital mode and AMPS analog mode. The PRL, however, does not account for the addition of the GSM mode to the wireless telephone. Therefore, it can be appreciated that there is a need for an apparatus and method to account for the addition of the GSM mode, so that the tri-mode (AMPS, CDMA, and GSM) wireless telephone can effectively attempt to acquire service in a particular geographic region. The present invention provides this and other advantages as will be apparent from the following description and accompanying figures.